That is because manhwa is from korea where lgbt+ is illegal, most site wouldn’t allow any lgbt+ content due to legal issues where they might get trouble with government or even majority of their user for promoting lgbt+.
I could recommend Bring the Love. It was a wholesome story.
I watched the kdrama Nevertheless entirely bc of the lesbian side couple and i believe it's adapted from a webtoon.
Spoiler alert tho
they don't end up together and it pissed me off
https://www.mangago.zone/read-manga/old_clothes_collection_bin_of_love/
I haven’t read it but I’m pretty sure it’s an sl with gl side couple
Manhwas where there’s a queer side couple? Or side queer characters? (Of any genre) I feel like I don’t see that often unless it’s in a bl or gl..